On 03/02/2019 19:19, Martin Gregorie wrote:
> On Sun, 03 Feb 2019 18:12:01 +0000, mm0fmf wrote:
>
>> On 03/02/2019 12:41, Martin Gregorie wrote:
>>> - Back in the MS-DOS days Bill Gates was on record as saying that
>>> nobody
>>>     could ever need more than 640 KB of RAM (the limit for an IBM
>>>     PC-AT).
>>
>> Perhaps you can give a reference for whatever leads you to believe that
>> to be a true statement because it was never said by W. Gates III?
>
> "Quote: No one will need more than 637 kb of memory for a personal
> computer. 640K ought to be enough for anybody."
> Date: 1981
>
> Bill Gates has faithfully denied he never said this, but the quote has
> taken on a life of its own and become synonymous with the Microsoft
> founder. Supposedly, he was quoted at a computer trade show in support of
> the IBM PC's 640KB RAM limit, which he'd been heavily promoting that
> year. Chances are he might have been misquoted, having originally said,
> "640K ought to be enough for anybody" at the time. A feature on the
> Huntsville Times website notes Gates response to the remark: "I've said
> some stupid things and some wrong things, but not that. No one involved
> in computers would ever say that a certain amount of memory is enough for
> all time." The majority agress he said something along the lines of 640KB
> of RAM sufficing for PC users. Take the L and move forward."
>
> - that's about the best I can find, but note that IBM PCs in that era
>    did have a physical limit of 640KB on the ram that could be installed.
>
> I do now wonder, though, if their display cards back then were memory-
> mapped and if so, how much of the unusable 360 KB of memory space they
> occupied.
>
Yes, they were.

IIRC there was addressing for 1MB of RAM, and the Bios sat at the very
top, and DOS addressed the fisrt 640k opnly, with video being above that
along with other perpiheral cards.

I/O of course in Intel is not memory mapped.

Later on the extra mameory could be mapped in.. before 32 bits came
along and the whole sorry mess was consigned to the dustbin of history



>


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